Turbine ring assembly with a sealing plate

Abstract

The invention relates to a turbine ring assembly (2) provided with a CMC sectorized turbine ring (4) and with a ring support structure (6), each sector (10) comprising a base (12) from which an upstream attachment tab (16) and a downstream attachment tab (14), which are axially spaced, extend radially outwards, the support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the attachment tabs (14, 16) are held. The assembly (2) further comprises, at each junction between two adjacent ring sectors (10) in the circumferential direction (Dc), a first cylindrical sealing element (42) extending mainly in the axial direction (DA) and arranged between the bases (12) of the two adjacent ring sectors (10), a second sealing element (124) extending radially along the downstream attachment tab (14) from the cylindrical seal (42), forming a sealed connection, and a third sealing element (126) extending radially along the downstream attachment tab (16) from the cylindrical seal (42), forming a sealed connection.

Description

[0001] Description

[0002] Title of the invention: Turbine ring assembly with a sealing sheet

[0003] Technical Field

[0004] A turbine ring assembly for a turbomachine is provided wherein the assembly comprises a plurality of angular ring sectors of ceramic matrix composite material placed end to end to form a turbine ring.

[0005] The field of application of the invention is in particular that of gas turbine aeronautical engines. The invention is however applicable to other turbomachines, for example industrial turbines.

[0006] Prior art

[0007] In the case of all-metal turbine ring assemblies, it is necessary to cool all the elements of the assembly and in particular the turbine ring which is subjected to the hottest flows. This cooling has a significant impact on the engine performance since the cooling flow used is taken from the primary flow of the engine. In addition, the use of metallic material for the turbine ring limits the possibilities of increasing the temperature at the turbine level due to the mechanical limitations specific to this type of material, which would nevertheless improve the performance of aeronautical engines.

[0008] In an attempt to resolve these problems, it was considered to make the turbine ring from a ceramic matrix composite (CMC) material in order to avoid the use of a metallic material.

[0009] CMC materials have good mechanical properties making them suitable for forming structural elements and advantageously retain these properties at high temperatures. The use of CMC materials has advantageously made it possible to reduce the cooling flow required during operation and therefore to increase the performance of turbomachines. In addition, the use of CMC materials advantageously makes it possible to reduce the mass of turbomachines and to reduce the effect of hot expansion encountered with metal parts. Documents FR 2 540 939 and FR 2 955 898 are also known, which disclose turbine ring assemblies.

[0010] The ring comprises an annular base whose inner face defines the inner face of the turbine ring and an outer face from which two legs extend radially, the ends of which are held between the two flanges of a metal ring support structure.

[0011] The integration of a CMC ring includes radial support of the part partly ensured by one or more axial pins. In the known document FR 3 086 327, there are four pins, two upstream and two downstream.

[0012] Using a CMC material for the ring significantly reduces the ventilation required to cool the turbine ring, thus increasing efficiency. They also allow for weight savings because they are lighter than the metal alloys traditionally used.

[0013] However, since CMC has a different mechanical behavior from a metallic material, its integration and the way of positioning it within the turbine had to be rethought. Indeed, CMC can be damaged by shrink-fit assemblies (usually used for metallic rings) and its thermal expansion is lower than that of a metallic material.

[0014] There is a need to improve existing turbine ring assemblies and their mounting, and in particular existing turbine ring assemblies using CMC material in order to reduce the intensity of mechanical stresses to which the CMC ring is subjected during turbine operation.

[0015] CMC turbine rings are generally divided into several ring sectors. This integration choice is due to the fact that a single-piece ring would deform under the effect of high temperatures for this high-pressure turbine part. This would result in a clearance at the tip of the moving blade (in the opposite vein) that is locally too large and thus significantly degraded performance via a loss of turbine efficiency.

[0016] The consequence of this sectorization of the turbine ring is the creation of inter-sector clearances (between 0.1 mm and 1 mm). To limit leaks in these areas, sealing strips (also called sheets) are generally integrated between the parts. Although their effectiveness is notable, it is necessary to machine slots at the inter-sectors of the CMC parts to integrate them.

[0017] However, since CMC is particularly hard, machining these slots is very long and complex.

[0018] Also known from document FR3034454 is a turbine ring assembly comprising a plurality of CMC ring sectors forming a turbine ring and a ring support structure. Each ring sector has a K shape in radial section, with tabs extending from the outer face of the annular base above the end portions of the annular base. The turbine ring assembly comprises a plurality of rigid seals each extending axially between two adjacent ring sectors, and elastic holding devices exerting a force capable of holding the seals in contact with the end portions or the tabs of two adjacent ring sectors.

[0019] The ring assembly described in this document presents a set of constraints of complexity and bulk that are too great for its integration, in particular because of the elastic holding devices used to hold the rigid joints and the thick tongue shape of the rigid joint which requires the provision of wide slots.

[0020] Statement of the invention

[0021] The main aim of the present invention is therefore to propose a turbine ring assembly which does not have the aforementioned drawbacks while having a reduced mass and further reducing the intensity of the mechanical stresses to which the CMC ring sectors are subjected during operation of the turbine.

[0022] More particularly, the solution of the present invention aims to limit wear at the level of the contacts between the CMC ring and the metal parts.

[0023] This aim is achieved by means of a turbine ring assembly comprising a plurality of ring sectors made of ceramic matrix composite material forming a turbine ring, defining an axial direction, a radial direction and a circumferential direction, and a ring support structure held by a turbine casing, each ring sector comprising a base from which an upstream attachment lug and a downstream attachment lug extend radially outwards axially spaced from one another, the ring support structure comprising an upstream radial flange and a downstream radial flange between which the upstream attachment lug and the downstream attachment lug of each ring sector are held.

[0024] The ring assembly further comprises, at each junction between two adjacent ring sectors in the circumferential direction, a first sealing means extending mainly in the axial direction and arranged between the bases of the two adjacent ring sectors, a second sealing means extending radially along the downstream attachment lug, and a third sealing element extending radially along the downstream attachment lug.

[0025] The turbine ring assembly according to the invention is remarkable in particular in that the first sealing element is a cylindrical seal, the second sealing element extends radially from the cylindrical seal forming a sealed connection, and the third sealing element extends radially from the cylindrical seal forming a sealed connection.

[0026] The second and third sealing elements serve both for sealing and locking the rollers. This eliminates the need for additional parts to hold these rollers in position in an area with high constraints on available volume.

[0027] The use of a cylindrical sealing gasket makes it possible to considerably reduce, or even eliminate, the sealing slots to be machined in the CMC ring sectors and therefore to gain in simplicity and manufacturing cost of the parts compared to the use of a sealing tab. Indeed, to integrate it, it is no longer necessary to machine a slot with a height of between 0.5 mm and 1.5 mm and a significant depth, but "only" to chamfer the faces at the inter-sectors to hold it or to machine a hemispherical groove.

[0028] The support between the cylindrical seal and the CMC ring sector is then made on a line, and no longer on a surface contrary to what was provided in the state of the art with tabs inserted in slots. The invention thus makes it possible to avoid the presence of a chemical interaction between the Nickel of the metal and the free silicon of the CMC in the high temperature operating conditions encountered in the HP Turbine environment. Indeed, tests have shown that the reduction of the contact surface has an effect of order 1 on the interaction between the materials.

[0029] Additionally, manufacturing a cylindrical gasket rather than a tab provides a wider gasket geometric variety to limit interaction.

[0030] The invention is also applicable to other integrations, including with metal ring sectors.

[0031] A cylindrical shape is understood to mean a three-dimensional geometric shape with a ruled surface whose generators are parallel, that is to say a surface in space made up of parallel lines.

[0032] According to a first aspect of the turbine ring assembly, the cylindrical seal may comprise, in a cutting plane orthogonal to the axial direction, a section with a diameter of between 0.5 mm and 5 mm.

[0033] According to a second aspect of the turbine ring assembly, each ring sector may comprise a first inter-sector face and a second inter-sector face, each inter-sector face comprising a zone of cooperation with the cylindrical seal at the base of the ring sector.

[0034] According to a third aspect of the turbine ring assembly, the cooperation zone may be formed by a bevel of the inter-sector face, or by a semi-cylindrical inter-sector groove.

[0035] Each semi-cylindrical inter-sector groove has a radius greater than the radius of the cylindrical seal, and between 0.25 mm and 3 mm.

[0036] Each bevel of the inter-sector face can form an angle between 10° and 80° in the radial direction. The machining of the bevel of the inter-sector face can be localized on the entire inter-sector face.

[0037] According to a fourth aspect of the turbine ring assembly, the first inter-sector face and the second inter-sector face of each ring sector may each comprise an upstream radial slot extending from the base to a portion of the height of the upstream attachment lug, a downstream radial slot extending from the base to a portion of the height of the downstream attachment lug, and the assembly may further comprise, at each junction between two adjacent ring sectors in the circumferential direction, an upstream sealing tab inserted into the upstream radial slots of the two adjacent ring sectors and a downstream sealing tab inserted into the downstream radial slots of the two adjacent ring sectors, the upstream and downstream sealing tabs being arranged radially outside the cylindrical seal.

[0038] Although this embodiment involves machining two slots, this is still two slots less than the four slots provided in the prior art, the four slots provided in the prior art being larger than the two slots in this embodiment. In addition, the tabs are further away from the vein and thus see temperatures outside the range of chemical interaction with the CMC.

[0039] Alternatively, the sealing tabs could be replaced by sealing rollers arranged radially in hemispherical grooves which would replace the radial slots.

[0040] According to a fifth aspect of the turbine ring assembly, the downstream sealing tab and the upstream sealing tab include a notch cooperating with the cylindrical seal to hold it radially in position.

[0041] According to a sixth aspect of the turbine ring assembly, the cylindrical seal is made from a metallic material selected from HA188®, Inco 750-X®, Waspaloy X®, and CMC.

[0042] According to a seventh aspect of the turbine ring assembly, to radially hold the ring sector in position with the ring support structure, the ring assembly comprising, for each ring sector, at least a first pin passing through the downstream attachment lug and the downstream radial flange and at least a second pin passing through the upstream attachment lug and the upstream radial flange.

[0043] According to an eighth aspect of the turbine ring assembly, the first pin and the second pin are two transverse pins, each transverse pin passing through the upstream hooking lug and the downstream hooking lug of the ring sector and the ring support to hold the ring sector and the ring support integral with each other.

[0044] The invention also relates to a turbomachine comprising an assembly as defined above.

[0045] Brief description of the drawings

[0046] [Fig. 1] Figure 1 is a schematic sectional view along a plane including the axial direction and the radial direction of a turbine ring assembly according to the invention.

[0047] [Fig. 2] Figure 2 shows a perspective view of a portion of the turbine ring assembly of Figure 1.

[0048] [Fig. 3] Figure 3 shows a zoom of the beveled part of an inter-sector face of the ring sector of Figure 2.

[0049] [Fig. 4] Figure 4 shows a first sectional view of a ring sector according to a second embodiment of the invention.

[0050] [Fig. 5] Figure 5 illustrates a second sectional view of a ring sector according to the second embodiment of the invention.

[0051] Description of the embodiments

[0052] Figure 1 schematically represents a turbine ring assembly 2 according to a first embodiment of the invention. Figure 1 is a sectional view along a plane comprising the radial direction D R and the axial direction D and orthogonal to the circumferential direction D c .

[0053] Figure 2 shows a perspective view of a portion of the turbine ring assembly of Figure 1.

[0054] The turbine ring assembly 2 shown in Figures 1 and 2 includes in particular a turbine ring 4 made of ceramic matrix composite (CMC) material centered on a longitudinal axis XX, a metal ring support structure 6 fixed to a turbine casing not shown for clarity. The turbine ring 4 surrounds a set of turbine blades not shown. the circumferential direction D cbeing a circular direction centered on the longitudinal axis XX.

[0055] Subsequently, throughout the text, the terms "upstream" and "downstream" are used in reference to the direction of flow of the gas stream F through the blades indicated by an arrow.

[0056] Furthermore, the turbine ring 4 is formed from a plurality of angular ring sectors 10 which are placed end to end in the circumferential direction to form a ring. In Figure 1, the arrow D A indicates the axial direction of the turbine ring while arrow D R indicates the radial direction of the turbine ring.

[0057] Each angular ring sector 10 has a section substantially in the shape of an inverted Pi (or ii) with a base 12 provided with an internal face 12a which defines an angular portion of the internal face of the turbine ring 4 and which is typically provided with a layer of abradable coating 13 also acting as a thermal and environmental barrier.

[0058] Two axially spaced attachment lugs, a downstream attachment lug 14 and an upstream attachment lug 16, extend radially from the outer face 12b of the base 12 opposite the inner face 12a. These attachment lugs 14 and 16 extend over the entire width of each ring sector 10 (in the circumferential direction).

[0059] The ring support structure 6 comprises a ferrule 60 extending around the axis XX, as well as an upstream radial flange 62 and a downstream radial flange 64 extending radially inward from the ferrule 60. The downstream radial flange 64 comprises an attachment portion 640 projecting radially from the ferrule 60, and the upstream radial flange 62 comprises an attachment portion 620 projecting radially from the ring 60, as well as a first upstream flange 20 and a second upstream flange 22 fixed to the attachment portion 620 projecting radially from the upstream radial flange 62 using bolts 300 and nuts 302. The first upstream flange 20 is arranged upstream of the second upstream flange 22. The bolts 300 axially pass through the first upstream flange 20, the second upstream flange 22 and the attachment portion 520 of the upstream radial flange 62.The upstream radial flange 62 and the downstream radial flange 64 thus form two attachment flanges for the ring 4 arranged axially between the downstream attachment lug 14 and the upstream attachment lug 16 of the ring sectors 10.

[0060] The turbine ring assembly 2 further comprises upstream pins 40 and downstream pins 50. The upstream pins 40 pass through the second upstream flange 22 of the upstream radial flange 62 as well as the upstream lug 16 of a ring sector 10. The downstream pins 50 pass at least partially through the downstream radial flange 64, and more particularly the radially projecting attachment portion 640, as well as the downstream attachment lug 14.

[0061] As illustrated in Figures 1 and 2, the ring assembly 2 further comprises at each junction between two adjacent ring sectors 10 along the circumferential direction D c, a cylindrical seal 42. The seal 42 is arranged between the bases 12 of the two adjacent ring sectors 10, and extends mainly in the axial direction D A , that is, the base of the cylindrical shape extends in a plane orthogonal to the axial direction D A and the generatrices of the cylindrical shape extend parallel to the axial direction D A .

[0062] Preferably, the base of the cylindrical shape forms a disc with a circular outer perimeter. The seal 42 comprises, in a section plane orthogonal to the axial direction D A , a circular section with a diameter between 0.5 mm and 5 mm.

[0063] In a variant where the base of the cylindrical shape has a shape other than a disc, the circular section of the sealing gasket 42 is inscribed in a circle whose diameter is between 0.5 mm and 5 mm.

[0064] Each ring sector 10 comprises a first inter-sector face 102a and a second inter-sector face (102b but not yet visible in FIG. 2), each inter-sector face 102a and 102b comprising a zone 104 of cooperation with the cylindrical seal 42 at the height of the base 12 of the ring sector 10. At each junction between two adjacent ring sectors 10, a seal 42 cooperates with the first inter-sector face 102a of a first ring sector 10 and the second inter-sector face 102b of a second ring sector 10. The zone 104 of cooperation is formed by a bevel 106 of the inter-sector face 102a or 102b.Consequently, each inter-sector face, both a first inter-sector face 102a and a second inter-sector face 102b, comprises three parts: a radially internal part 105, a radially external part 107 and an intermediate part 106 forming the bevel and located radially between the radially internal part 105 and the radially external part 107, as shown in Figures 1 and 2 and in Figure 3 which shows a zoom of the beveled part of an inter-sector face of the ring sector of Figure 2.

[0065] The radially internal part 105 and the radially external part 107 of the same inter-sector face are parallel to each other but axially offset. According to the circumferential direction D c, the radially inner portion 105 of an inter-sector face is closer to the adjacent ring sector 10 than the radially outer portion 107 of the same inter-sector face. In other words, on a ring sector 10, the distance along the circumferential direction D c separating the radially internal part 105 of the first inter-sector face 102a of the ring sector 10 from the radially internal part 105 of the second inter-sector face 102b of the same ring sector 10 is greater than the distance in the circumferential direction D c separating the radially external part 107 of the first inter-sector face 102a of the ring sector 10 from the radially external part 107 of the second inter-sector face 102b of the same ring sector 10.

[0066] Each bevel 106 of an inter-sector face can form an angle oc of between 10° and 80° relative to the radial direction [ft. The machining of the bevel of the inter-sector face extends over the entire inter-sector face in the axial direction D.

[0067] As illustrated in Figures 1 and 2, the first inter-sector face 102a and the second inter-sector face 102b of each ring sector 10 each comprise an upstream radial slot 116 extending from the base 12 to a portion of the height of the upstream hooking tab 16, and a downstream radial slot 114 extending from the base 12 to a portion of the height of the downstream hooking tab 14.

[0068] The downstream and upstream radial slots 114 and 116 each extend from the bevel. The ring assembly 102 further comprises, at each junction between two adjacent ring sectors 10 in the circumferential direction D c, an upstream sealing tab 126 inserted into the upstream radial slots 116 of the two adjacent ring sectors 10 and a downstream sealing tab 124 inserted into the downstream radial slots 114 of the two adjacent ring sectors, the upstream and downstream sealing tabs 126 and 124 being arranged radially outside the seal 42.

[0069] The downstream sealing tab 124 and the upstream sealing tab 126 comprise a notch 130 cooperating with the seal 42 to hold it radially in position.

[0070] The seals 42 are made from a metallic material selected from HA188®, Inco 750-X®, Waspaloy X®, and CMC.

[0071] Figures 4 and 5 show two sectional views of a ring sector according to a second embodiment of the invention.

[0072] The second embodiment differs from the first embodiment in that the zone 104 of cooperation of the ring sector 10 with the seal is not a bevel but a semicircular groove 109 in which is partially inserted in the circumferential direction D c , the seal 42.

[0073] Each semi-cylindrical groove 109 has a radius greater than the radius of the seal, and between 0.25 mm and 3 mm.

[0074] In a variant not shown, the sealing tabs could be replaced by sealing rollers, similar to gaskets in design, arranged radially in hemispherical grooves which would replace the radial slots.

[0075] The present invention thus provides a turbine ring assembly with reduced mass and further reducing the intensity of the mechanical stresses to which the CMC ring sectors are subjected during operation of the turbine.

Claims

Claims

1. Turbine ring assembly (2) comprising a plurality of ring sectors (10) made of ceramic matrix composite material forming a turbine ring (4), defining an axial direction (D A ), a radial direction (D R ) and a circumferential direction (D c), and a ring support structure (6) held by a turbine casing, each ring sector (10) comprising a base (12) from which an upstream hooking lug (16) and a downstream hooking lug (14) extend radially outwards, axially spaced from each other, the ring support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the upstream hooking lug (16) and the downstream hooking lug (14) of each ring sector (10) are held, the ring assembly (2) further comprising, at each junction between two adjacent ring sectors (10) in the circumferential direction (D c ), a first sealing element (42) extending mainly in the axial direction (D A) and arranged between the bases (12) of the two adjacent ring sectors (10), a second sealing element (124) extending radially along the downstream attachment lug (14), and a third sealing element (126) extending radially along the downstream attachment lug (16), characterized in that the first sealing element (42) is a cylindrical seal, the second sealing element (124) extends radially from the cylindrical seal (42) forming a sealed connection, and the third sealing element (126) extends radially from the cylindrical seal (42) forming a sealed connection.

2. Turbine ring assembly (2) according to claim 1, wherein the seal (42) comprises, in a section plane orthogonal to the axial direction (DA), a section with a diameter between 0.5 mm and 5 mm.

3. Turbine ring assembly (2) according to one of claims 1 or 2, in which each ring sector (10) comprises a first inter-sector face (102a) and a second inter-sector face (102b), each inter-sector face (102a, 102b) comprising a cooperation zone (104) with the seal (42) at the height of the base (12) of the ring sector (10).

4. Turbine ring assembly (2) according to claim 3, in which the cooperation zone (104) is formed by a bevel (106) of the inter-sector face (102a, 102b).

5. Turbine ring assembly (2) according to claim 3, in which the cooperation zone (104) is formed by a semi-cylindrical inter-sector groove (109).

6. Turbine ring assembly (2) according to one of claims 3 to 5, in which the first inter-sector face (102a) and the second inter-sector face (102b) of each ring sector (10) comprise an upstream radial slot (116) extending from the base (12) to a portion of the height of the upstream attachment lug (16), a downstream radial slot (114) extending from the base (12) to a portion of the height of the downstream attachment lug (14), and the assembly (3) further comprising, at each junction between two adjacent ring sectors (10) in the circumferential direction (D c), an upstream sealing tab (126) inserted into the upstream radial slots (116) of the two adjacent ring sectors (10) and a downstream sealing tab (124) inserted into the downstream radial slots (114) of the two adjacent ring sectors (10), the upstream and downstream sealing tabs (124, 126) being arranged radially outside the seal (42).

7. A turbine ring assembly (2) according to claim 6, wherein the downstream sealing tab (124) and the upstream sealing tab (126) comprise a notch (130) cooperating with the seal (42) to hold it radially in position.

8. A turbine ring assembly according to one of claims 1 to 7, wherein the seal (42) is made from of a metallic material selected from A600®, Hastelloy X®, HA188®, and HS25®.

9. Turbine ring assembly (2) according to one of claims 1 to 8, wherein to radially hold the ring sector (10) in position with the ring support structure (6), the ring assembly (2) comprising, for each ring sector (10), at least one first pin (50) passing through the downstream attachment lug (14) and the downstream radial flange (64) and at least one second pin (40) passing through the upstream attachment lug (16) and the upstream radial flange (62).

10. A turbine ring assembly according to claim 9, wherein the first pin (50) and the second pin (40) are two transverse pins, each transverse pin passing through the upstream attachment lug (16) and the downstream attachment lug (14) of the ring sector (10) and the ring support (6) to hold the ring sector (10) and the ring support (6) secured to each other.

11. Turbomachine comprising an assembly (2) according to any one of claims 1 to 10.

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